Syria on Sunday denied UN claims that government forces used heavy weapons during a military operation that has brought widespread international condemnation against President Bashar al-Assad's rule.

Syrian Foreign Ministry spokesman Jihad Makdissi said the violence on Thursday was not a massacre, but a military operation targeting armed fighters who had taken control of the village of Tremseh.

"What happened wasn't an attack on civilians," Makdissi told reporters in Damascus. "What has been said about the use of heavy weapons is baseless."